The invention relates to an item of railroad rolling stock which when desired, can travel on a highway as a normal highway truck trailer.
More particularly, it relates to a rail-operable semi-trailer which can be converted to a road-operable semi-trailer, or vice versa (a road-operable semi-trailer which is convertible to a rail-operable semi-trailer).
The notion of devising a vehicle adapted to travel on both roads and rails is not new. In the U.S., attempts in this direction were made around the end of the 1950s.
At the end of the 1970s, cars were implemented which were furnished with a single rectractable rail-operable axle mounted on one end of the car, whereby pneumatic tires could take over for the rail-operable wheels.
Such a system was not practicable in Europe because the maximum weight allowed on a single rail-operable axle was 20 or 22.5 tons, whereas in the U.S., 27-30 tons per axle is allowable.
It is permissible for highway trailers to have a gross weight of 36 (+5%) tons in some European countries, including Italy. This weight must be distributed among the front and rear wheels, however, and therefore such a system cannot function with a single rail-operable axletree, i.e., in the form of a rail-operable semi-trailer, without strict limitations being placed on payload during the rail travel.
Furthermore, such systems (with retractable rail-operable axletree) have increased weight due to the provision of the retractable rail-operable axletree itself, and thereby have reduced carrying capacity of the semi-trailer when on the highway.
In any event, this concept of a bimodal car for road and rail persisted, and recently a different type of vehicle has come into use which is adapted to travel on both roads and rails, wherein the car does not carry the rail-operable axles and wheels when traveling on roads, and when the car is to be used on rails, it is lowered onto one or more ordinary, standard-type trail trucks. The highway carriage remains connected to the semi-trailer, but its wheels are retracted upward to a suitable height above the rails, by means of a suitable device.
However, this more recent system also has certain drawbacks, due to the highway regulations of some European countries, particularly Italy, where the maximum weight of a highway semi-trailer is about 38 tons, and the maximum speed of a semi-trailer on a railroad when employing a standard reinforced rail truck is 90 km/hr. Moreover, the 38 tons plus 5 tons for the weight of the rail truck amounts to 43 tons, which is 21.5 tons per axle of the rail truck; and this weight is impermissible on all rail lines in Europe.
Stated differently, any time the semi-trailer can travel on roads at a total weight greater than 35 tons, not only is it impermissible to convert it into a semi-trailer which is rail-operable at a speed greater than 90 km/hr, but it is also necessary to employ a reinforced rail truck which weighs more and thereby lowers the payload.
Moreover, such a bimodal semi-trailer for road and rail, having a transportable rail truck, has additional disadvantages in practice.
The coupling presently used to couple together such semi-trailers for rail travel with a single rail truck, so that the semi-trailer operates as a rail-operable semi-trailer, is of the rigid type for horizontal coupling. Accordingly, to establish the coupling, it is necessary to coordinate the position for the hole receiving the locking pin, and this coordination must be effected both horizontally and vertically. This situation requires regulation of the height of the support props during the maneuver, and generally requires an operator for the insertion of the locking pin unless automatic means are provided.
Further, the fixing of the center-bearing counter-element of the semi-trailer to the center pin socket of the rail truck is carried out by a bar and a bracket which must be applied from the bottom, thereby requiring the operator to perform an awkward, arduous maneuver, or else requiring the provision of a pit between the tracks where the said operator can work more conveniently.
The pneumatic connection of the brake cylinder to the respective distributor of compressed air (or more generally, to the remainder of the pneumatic system) is a manual operation. If this connection is not made (e.g., due to operator error or oversight), the braking of the rail truck will be disabled.
Other disadvantages are connected with the fact that the semi-trailer can be aligned with the axis of the tracks only with the aid of the locomotive, and locomotive engineer must perform difficult maneuvers for this.
The general aim of the invention is to eliminate the above-mentioned disadvantages in a binary semi-trailer for traveling on roads and rails.
The principal specific object of the invention is to provide a binary semi-trailer whereby the empty weight can be reduced for both rail and road travel, by replacing the highway carriage by the rail truck, or vice versa, as required, such that only the highway carriage is present when traveling on roads, and only the rail truck is present when traveling on rails.
A second important specific object of the invention is to provide a binary semi-trailer wherein all means required for rail travel are dismounted when the highway carriage is connected in fixed mode to the semi-trailer.
A third important specific object of the invention is to provide a coupling between the semi-trailers which enables formation of railroad trains, which operates relatively rapidly and reliably.
The first and second specific objects are achieved by a semi-trailer in which the highway carriage is removable, i.e., the highway carriage is furnished with its own independent frame which incorporates coupled elastic suspensions and pneumatic and/or hydraulic lifting means, and is furnished with means of attaching it quickly to the semi-trailer which is adapted therefor.
The third specific object is achieved by a coupling system between the rail-operable semi-trailers which system simplifies the manuevers for forming a railroad train which maneuvers are carried out by the locomotive; and said coupling system is furnished with blocks, runners, pads or the like which prevent rolling movements of the semi-trailer around its longitudinal axis.